Splash-resistant injection device

ABSTRACT

An injection device including a housing and a delivery element guided in a liquid-tight manner in relation to the housing, the delivery element having a substantially smooth, cylindrical outer wall region and surrounded by at least one annular sealing element.

CROSS-REFERENCED RELATED APPLICATIONS

This application is a continuation of International Patent ApplicationNo. PCT/CH2007/000240 filed May 11, 2007, which claims priority to SwissPatent Application No. 1475/06 filed Sep. 15, 2006, the entire contentsof both of which are incorporated herein by reference.

BACKGROUND

The present invention relates to devices for injecting, administering,delivering, infusing or dispensing a substance, and to methods of makingand using such devices. More particularly, it relates to a device foradministering a fluid product or substance. In some embodiments, thedevice may be an injection device for the injection of an adjustabledose of the product and, in some embodiments it may be an injection pen,i.e. a compact injection device in a pen-like configuration.

A large number of injection devices are known from the prior art for thedosed administering of medicaments or therapeutic substances such asinsulin, growth hormones or osteoporosis drugs, which must beadministered regularly. Such devices are, on one hand, intended toprecisely deliver a dose which is able to be pre-set. On the other hand,they are intended to be reliable in operation and user-friendly to ahigh degree. This applies all the more because they are generallyoperated by the patient for self-administration of a therapeutic agentor medicament.

The medicament can be housed in an exchangeable carpule (which also maybe thought of and/or referred to as an ampoule, receptacle, container orreservoir), which is able to be inserted into a carpule holder. Thelatter can then be associated with or fastened to a housing of theinjection device, e.g. by a screw connection, bayonet connection, etc.For distribution, a product stopper or piston in the carpule is pushedforward, toward a needle carried by the injection device, by a deliveryarrangement with a delivery element in the form of a piston rod.

Compact, pen-shaped administering devices are known, in which thedistribution takes place automatically after a first triggering(“power-assisted pens”). The dose in such devices is generally pre-setby a rotation of a dosing button. A drive is present in the device, e.g.a spring drive, which is tensioned on setting of the dose. The device istriggered by pressing a triggering button, which can be identical to thedosing button. In so doing, the drive generates a drive movement, e.g.in the form of a rotary movement, which is converted into an advancingmovement of the piston rod. In the case of a drive by a rotary movement,the piston rod may be constructed as a threaded rod on which a drive nutruns.

In DE-A 10 2004 063 644, DE-A 10 2004 063 647, WO-A 2004/002556 and DE-A102 29 122 injection devices are disclosed, which constitute the generalprior art for the present invention.

On changing or replacing the receptacle, the piston rod canunintentionally come in contact with fluids or other substances, e.g. aspilled liquid, a broken receptacle containing a fluid medicament.Thereby, fluid could penetrate into the interior of the injection deviceand impair its function.

SUMMARY

It is, therefore, an object of the present invention to provide anadministering device which prevents or at least minimizes an inadvertentpenetration of fluid or liquid into the interior of the device.

In one embodiment, the present invention comprises an injection devicecomprising a housing and a delivery element guided in a liquid-tightmanner in relation to the housing, the delivery element having asubstantially smooth, cylindrical outer wall region and surrounded by atleast one annular sealing element.

In one embodiment according to the present invention, a device for theadministering of a fluid product comprises a housing and a deliveryelement for delivering the product out of a reservoir. The deliveryelement extends from the interior of the housing outward and is movablerelative to the housing. The delivery element is sealed so as to befluid-tight, at least protected against splashed fluid or liquid, withrespect to the housing or to an element fixed to the housing. Thereby, apenetration of fluids is effectively prevented.

In some embodiments, a corresponding seal can be constructed directlybetween the delivery element and the housing. However, it is alsoconceivable that a first seal is constructed between the deliveryelement and an element which is movable relative to the housing, and asecond seal is constructed between the movable element and the housing.The movable element can be arranged so that it is only movable when thereservoir is being changed, and is immovable with respect to the housingduring the actual administering. It can, in particular, besleeve-shaped, e.g. generally cylindrical.

In some embodiments, the delivery element has a substantially smooth,cylindrical, circular cylindrical outer wall region, which is surroundedby at least one ring-shaped sealing element. In this way, a simple andefficient sealing can be achieved, as is not possible in the case ofprior art piston rods with external thread. The length of the smoothouter wall region corresponds at least to the distance between a distalfinal position and a proximal initial position, between which thedelivery element is movable in the course of the administering, toensure a sealing over this entire region. A “substantially smooth” outerwall region is to be understood to mean a region in which no structuressuch as threads or grooves are present, which oppose or interfere withan efficient sealing effect. On the other hand, the outer wall regioncould have fine structures, e.g. scales, a pattern or texture, in therange below 100 micrometres, e.g., below 10 micrometres, which aresuited to at least not impairing the sealing effect, or even toimproving it, e.g., a micro- or nano-structuring. These structures couldhave a preferred direction to inhibit a flow of fluids.

In some embodiments, the at least one ring-shaped sealing elementcomprises at least one circumferential, flexible sealing lip, whichrests on the cylindrical outer wall region and acts in the manner of awindscreen wiper or as a stripper. The contact angle between the sealinglip and the outer wall region amounts to less than 90 degrees. However,it can also be constructed as a ring with a round or polygonalcross-section.

In some embodiments, the delivery element is guided and locked againstrotation relative to the housing. Thereby, a sealing is simplifiedcompared with a delivery element which carries out a combinedtranslation- and rotation movement. The delivery element is driven by arotary movement, e.g. via a thread connection with a rotatable element.For this, the administering device comprises a drive arrangement toproduce the rotary movement relative to the housing, with the rotarymovement bringing about in a suitable manner a thrust movement of thedelivery element along the thrust axis.

In some preferred embodiments, to make a substantially smooth outer wallregion possible, the delivery element has an internal thread, the threadaxis of which runs or extends along the thrust axis. Thereby, the threadwhich is used for the drive is placed inward and a configuration of theouter side of the delivery element which is adapted to the requirementsof sealing is made possible. A thread element with an external thread isthen in engagement with the internal thread. This thread element is ableto be fixed relative to the housing along the thrust axis and is able tobe set in a rotational movement about the thrust axis by the drivearrangement to advance the delivery element along the thrust axis.

In some preferred embodiments, the interior of the housing is sealed ina fluid-tight manner completely with respect to the exterior of thehousing, i.e. not only in the region in which the delivery element isguided outward, but also in other regions, e.g. in the region of movabledosing- or actuating elements.

In some embodiments, the delivery element and/or an element cooperatingtherewith in a sealing manner can consist of a hydrophobic material orbe coated hydrophobically to achieve or improve a sealing effect, byavoiding a creep by capillary effect.

In some embodiments, a device in accordance with the present inventioncan further comprise at least one ball bearing which absorbs forceswhich are transmitted between the delivery element and the housing.Frictional losses which are caused during the administering owing to thetransmission of forces between the delivery element and the housing arelargely minimized.

A ball bearing may be advantageous when the device in accordance withthe present invention comprises at least one rotatable elementcooperating with the delivery element and a drive arrangement forgenerating a rotary movement of the rotatable element relative to thehousing, with the rotary movement of the rotatable element bringingabout a (e.g. linear) thrust movement of the delivery element along thethrust axis in a distal direction, e.g. by a threaded engagement, whichis non-locking. In this case, the ball bearing is arranged such that itabsorbs (axial) forces acting along the thrust axis, which aretransmitted from the delivery element (locked with respect to rotationrelative to the housing) via the rotatable element to the housing, i.e.which act between the rotatable element and the housing. Expressed ingeneral terms, axial forces, acting in proximal (rearward) direction,are therefore transmitted between the delivery element and the housingvia a rotatable connection which is secure with respect to displacementin axial direction. For this, in the prior art, generally a slidingconnection is provided between the rotatable element and the housing oran element which is fixed to the housing. In the present invention, onthe other hand, at least one ball bearing is provided, which is arrangedbetween the rotatable element or an element connected therewith on theone hand, and the housing or an element which is fixed to the housing atleast during the administering, on the other hand. Thereby, frictionallosses during the rotation of the rotatable element can be avoided.

In some preferred embodiments of the present invention, two ballbearings are present, which are arranged so that they can absorb forcesalong the thrust axis in both the proximal and distal directions, distal(or froward) being the direction in which the thrust takes place. Axialforces in the proximal direction occur generally during theadministering, whereas axial forces in the distal direction can occurwhen the delivery element is spring-loaded in the distal direction, asis the case in a preferred embodiment. The spring serving for this issufficiently weak that it does not cause any ejection of the product outof the reservoir. Rather, it serves, in a change of reservoir, toautomatically bring the delivery element into its distal final position,i.e. to extend it completely, when the reservoir is removed from thehousing. When the delivery element is in a suitable connection with therotatable element, this leads to the rotatable element being set into arotation when the delivery element moves out due to the spring force. Tokeep the spring force small, a ball bearing is advantageous because withthe extending of the delivery element, it minimizes the frictionalforces acting then.

In some preferred embodiments of a device in accordance with the presentinvention can be developed as follows: The delivery element isconstructed in a sleeve shape with a proximal and a distal end and hasan internal thread. The delivery element is guided along the thrustdirection locked against relative rotation with respect to the housing.It is movable (axially) between a proximal and a distal final positionalong the thrust direction. The rotatable element has an external threadwhich cooperates with the internal thread of the delivery element.

In a preferred embodiment, such a delivery element with an internalthread is surrounded radially at least partially by a guide sleeve witha proximal and a distal end. The length of this guide sleeve correspondsat least to the maximum thrust range of the delivery element, i.e. thedistance between the distal and the proximal final position of thedelivery element. Close to its distal end, the guide sleeve isconnected, at least during the administering, so as to be locked againstrelative rotation with the housing or with an element fixed to thehousing. The delivery element is guided along the thrust direction so asto be locked against relative rotation in the guide sleeve. The deliveryelement, at least in the region of its proximal end, is in anengagement, locked against relative rotation, with the interior of theguide sleeve, which engagement, however, permits an axial displacement.In the region of the proximal end, an engagement structure, e.g. in theform of several longitudinal ribs, can be constructed projectingradially outwardly from the outer peripheral surface of the deliveryelement, cooperating with a complementary structure, e.g. in the form ofseveral longitudinal grooves on the inner peripheral surface of theguide sleeve. The device then comprises in addition an outer sleeve witha proximal and a distal end, which in turn radially surrounds the guidesleeve at least partially. Close to its proximal end, this outer sleeveis connected with the rotatable element. Close to its distal end, theouter sleeve is rotatable via the at least one ball bearing and isguided so as to be secured with regard to displacement relative to theguide sleeve.

Some considerations forming the basis of the embodiment(s) described inthe previous paragraph can be summarized as follows: The deliveryelement is to be secured against rotation relative to the stationaryhousing and guided longitudinally. Here, the delivery element is formedon its outer side as desired, substantially smooth or otherwise. Thismeans that the delivery element is only guided longitudinally in theregion of its proximal end in an element which is locked againstrelative rotation with respect to the housing. However, this in turnrequires that this element, which is locked against relative rotation,is at least sufficiently long that the guiding is also ensured over theentire range of the thrust of the delivery element. To ensure this, asleeve-like structure of the element which is locked against relativerotation is selected, which is therefore designated as a guide sleeve,with a length of this guide sleeve which corresponds at least to thethrust range of the delivery element. To drive the delivery element,furthermore, the rotatable element is arranged inside the deliveryelement. So that a thread engagement is ensured over the entire thrustrange, the rotatable element extends at least over a length of proximalto distal into the delivery element which corresponds to the thrustrange. Access to the rotatable element exists from the proximal end. Adriving of the rotatable element therefore takes place over its proximalend. At the same time, the rotatable element is mounted in any mannerrelative to an element which is fixed to the housing. This mounting mustbe able to absorb axial forces, because axial forces are transmittedfrom the delivery element via the thread engagement to the rotatableelement. In fact, a mounting could be provided directly at the proximalend of the rotatable element. However, this would take up a large amountof space in a region which is to be available as far as possible forother functions. It is therefore desirable to reposition the site of thebearing to another location, as close as possible to one of the ends ofthe housing. This takes place by the outer sleeve being securelyconnected with the rotatable element and continuing, as it were, alongthe outer side of the guide sleeve toward the distal direction. Themounting then takes place between the outer sleeve and the guide sleeve,and namely in the region of the distal end of the outer sleeve. Thereby,a very compact unit is created, the mounting of which, taking up arelatively large amount of space radially, comes to lie in a proximalregion, where it is only slightly intrusive, and which makes it possibleto accommodate further elements of the injection device in the radialintermediate space between the outer sleeve and the housing.Furthermore, the fact that the outer sleeve (and thus the rotatableelement) is mounted on the guide sleeve and not, for instance, on thehousing itself, makes it possible that the entire unit of guide sleeve,outer sleeve, mounting, rotatable element and delivery element can beformed so as to be movable systematically with respect to the housing,e.g. in the changeover of a receptacle.

In some preferred embodiments, the reservoir is held in a receptacleholder which is able to be fastened to the housing in a detachablemanner. On fastening, this receptacle holder is guided with respect tothe housing such that relative to the housing it carries out a combinedrotary movement about a rotation axis and a translation movement alongthe rotation axis. The device then further comprises a spring elementand a detent element. These elements are arranged such that the springelement produces a spring force on the detent element actingsubstantially along the rotation axis. The detent element therebycreates, in a predetermined holding position of the receptacle holder, adetachable detent connection by which the receptacle holder is fixedrelative to the housing. For this, for example, a projection of thedetent element can project into a depression of the receptacle holder orof an element which is locked against relative rotation with respectthereto. A reverse arrangement is also conceivable. The detentconnection is configured so that it is able to be detached again througha movement of the receptacle holder relative to the housing which isopposed to the movement on fastening, i.e. the detent connection doesnot need to be unlocked manually.

Therefore, in some preferred embodiments, a connection in the manner ofa screw or bayonet connection is provided between the receptacle holderand the housing or between elements connected with these. Inconventional bayonet connections between two elements, generally anelement with a bayonet pin is guided in a suitably formed slit or in acorresponding groove in the manner of a connecting link guide of theother element, until the bayonet pin reaches a final position(corresponding to the holding position). In such connections, anunintentional sliding back of the pin out of the final position may be aproblem. A similar problem also occurs in screw connections which arefixed by a clamping force and which can likewise become detachedunintentionally. The present invention addresses this by providing anaxially spring-loaded (and axially movable) detent element. Such adetent element ensures a defined fixing of the receptacle holder in theholding position, without the risk of an unintentional detachment. Theconnection is only detachable again by overcoming a sufficiently greatforce. Thus an abrasion which could lead to a wearing out of theconnection is avoided. By the detent element being spring-loaded intothe axial direction, a simple and space-saving development of the detentelement and of the spring element is made possible.

In some embodiments of the present invention, the receptacle will be acontainer with a cylindrical wall region and a stopper or pistondisplaceable therein, a so-called carpule or ampoule, which defines alongitudinal direction and is housed in a receptacle holder with acorrespondingly elongated form. When fastening on the housing, thereceptacle holder is rotated about this longitudinal direction, i.e. therotation axis coincides with the longitudinal axis. For theadministering of the product, the stopper is advanced by the deliveryelement along the longitudinal direction. Expressed more generally, thethrust direction of the delivery element therefore corresponds to adirection along the rotation axis about which the receptacle holder isrotated during its fastening or insertion into an injection device.

Various possibilities exist for the arrangement of the spring- anddetent element. According to a preferred embodiment, the detent elementis locked against relative rotation with respect to the housing and inthe detent position it is detachably engaged with an element which islocked against relative rotation with respect to the receptacle holder.In other words, the detent element does not follow the rotation of thereceptacle holder, but remains locked against relative rotation withrespect to the housing on fastening of the receptacle holder. However,the reverse arrangement is also conceivable, in which the detent elementis locked against relative rotation with respect to the receptacleholder.

In a preferred embodiment, the device comprises a carrier element. Thecarrier element is guided with respect to the housing such that onfastening of the receptacle holder on the housing and on detaching thereceptacle holder from the housing it is entrained by the receptacleholder and is set into a movement which comprises a rotary movementabout the rotation axis. The delivery element is then sealed withrespect to the carrier element by a first seal, and the carrier elementis sealed with respect to the housing by a second seal. The carrierelement can be fixable relative to the housing in at least onepredetermined position, e.g. by a detachable detent connection, as wasdescribed above. The carrier element in turn holds the receptacleholder. The receptacle holder is in this case therefore fixed indirectlyrelative to the housing by the carrier element.

In one embodiment, an injection device in accordance with the presentinvention comprises a guide element arranged to be locked againstrelative rotation with respect to the housing, which guide element canbe constructed as a guide sleeve. This guide element can be rigidlyconnected with the housing, can be produced integrally therewith, or itcan be displaceable axially with respect to the housing. The carrierelement, which can likewise be formed as a sleeve and can be thought ofor designated as a bayonet sleeve, is connected at least rotatably withthe guide element. The spring element and the detent element arearranged to be locked against relative rotation with respect to theguide element, and in the holding position of the receptacle holder thedetent element is engaged detachably with the carrier element. The guideelement can be connected to be locked against relative rotation andaxially displaceable with respect to the housing and the carrier elementcan be connected rotatably, but axially secure as regards displacement,with the guide element. Through this configuration, further parts of thedevice, arranged in the housing, which are connected with the guideelement, are displaced axially, when the receptacle holder is mounted onthe housing. Thereby, the administering device can be automaticallyreset on detaching of the receptacle holder and on fastening of thereceptacle holder the device can be brought into a state ready foroperation again. Thus it is possible, on detaching of the receptacleholder, to move the interior of the device (e.g. the drive arrangementand if applicable a triggering arrangement connected therewith) in adistal direction, so that the triggering arrangement, which can beformed as a push button, is drawn into the housing and thus indicatesthat the device is not ready for operation.

In some preferred embodiments, the carrier element is guided withrespect to the housing such that on fastening of the receptacle holderto the housing it is entrained by the receptacle holder and is set intoa combined rotational movement relative the housing about the rotationaxis and translation movement along the rotation axis in a proximaldirection.

In some preferred embodiments, the carrier element is moveable betweentwo defined final positions, and the detent element brings about in bothpositions a detachable detent connection, by which the carrier elementis fixed relative to the housing. The carrier element assumes its firstfinal position, when the receptacle holder assumes its holding position,and it assumes its second final position when the receptacle holder isremoved from the housing. In some preferred embodiments, the detentelement is detachably engaged directly with the carrier element both inthe first final position and also in the second final position.

In some preferred embodiments, the carrier element is guided in at leastone guide slit relative to the housing, i.e. on the actual housingitself or on an element which is fixed to the housing, by one or morecorresponding pins. Likewise, on fastening to the housing, thereceptacle holder is guided in at least one guide slit, in the manner ofa bayonet connection, relative to the housing.

In some preferred embodiments, the detent element is constructed in theform of a ring which extends around the rotation axis and/or around thethrust element. Suitable detent noses can be constructed on the ring.This detent element can be axially spring-loaded by a separate springelement. This may be, for example, a helical spring which is subjectedto pressure, or another type of elastic element. However, in somepreferred embodiments, the spring element has the form of a ring whichextends around the rotation axis and is curved about an axisperpendicularly to the rotation axis, so that the spring force isproduced by a compressing of the spring element along the rotation axis.

In some preferred embodiments, the detent element is constructedintegrally with the spring element. This leads to a simple development.In some embodiments, the detent element can be constructed as aprojection, protruding in the direction of the rotation axis, on thespring element. This embodiment may be advantageous when the springelement, as described above, has the form of a curved ring.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective exploded view of an exemplary embodiment of aninjection device according to the present invention;

FIG. 1B is a detail view of a surface structure provided on the thrustsleeve;

FIG. 2 is a longitudinal section through the injection device of FIG.1A;

FIG. 3 is an enlarged cut-out of FIG. 2;

FIG. 4 is a longitudinal section through an arrangement of a guidesleeve and of a coupling sleeve in the injection device of FIG. 1A;

FIG. 5A is a top view onto a ball bearing ring;

FIG. 5B is a sectional view of the ball bearing ring in the plane A-A;

FIG. 6 is a perspective view of a coupling sleeve;

FIG. 7 is a longitudinal section through selected parts of the injectiondevice of FIG. 1A;

FIG. 8 is a perspective illustration of a bayonet sleeve;

FIG. 9A is a top view onto a bayonet spring;

FIG. 9B is a side view of the bayonet spring of FIG. 9A;

FIG. 9C is a perspective view of the bayonet spring of FIG. 9A;

FIG. 10 is a longitudinal section through selected parts of theinjection device of FIG. 1A;

FIG. 11A is a longitudinal section through selected parts of theinjection device of FIG. 1A with a dose limiting ring in its finalposition;

FIG. 11B is a longitudinal section through selected parts of theinjection device of FIG. 1A with the dose limiting ring in its initialposition;

FIG. 12A is a perspective view of a coupling shaft with a dose limitingring of the injection device of FIG. 1A;

FIG. 12B is the parts of FIG. 12A in an exploded view;

FIG. 12C is the coupling shaft of FIG. 12A in a perspective view fromanother direction of view;

FIG. 13 is an exploded view of an arresting sleeve, a coupling springand a support ring;

FIG. 14 is a perspective view of selected parts of the injection deviceof FIG. 1A;

FIG. 15 is a perspective exploded view of the proximal end of theinjection device of FIG. 1A;

FIG. 16 is a longitudinal section through the injection device of FIG.1A in the initial position;

FIG. 17 is the longitudinal section of FIG. 16 after a first increase ofdose up to half the maximum dose;

FIG. 18 is the longitudinal section of FIG. 16 after a first increase ofdose up to the full maximum dose;

FIG. 19 is the longitudinal section of FIG. 16 after a first triggeringand a second increase of dose;

FIG. 20 is a longitudinal section through the injection device of FIG.1A after a complete emptying of the carpule;

FIG. 21 is a longitudinal section through an injection device accordingto another embodiment.

DETAILED DESCRIPTION

With regard to fastening, mounting, attaching or connecting componentsof the present invention, unless specifically described as otherwise,conventional mechanical fasteners and methods may be used. Otherappropriate fastening or attachment methods include adhesives, weldingand soldering, the latter particularly with regard to the electricalsystem of the invention, if any. In embodiments with electrical featuresor components, suitable electrical components and circuitry, wires,wireless components, chips, boards, microprocessors, inputs, outputs,displays, control components, etc. may be used. Generally, unlessotherwise indicated, the materials for making the invention and/or itscomponents may be selected from appropriate materials such as metal,metallic alloys, ceramics, plastics, etc. Generally, unless otherwiseindicated, relative positional or orientational terms (e.g., upwardly,downwardly, above, below, etc.) are intended to be descriptive, notlimiting.

FIG. 1A depicts an injection device in the form of an injection pen in aperspective exploded view. FIG. 2 shows the device in longitudinalsection. The following description relates to the device in theassembled state, as is illustrated in FIG. 2.

The injection device has a housing sleeve 20 in which a mechanism ishoused for setting and distributing a dose. The housing sleeve 20 hassubstantially the form of a circular cylinder and defines a longitudinalaxis. A receptacle holder in the form of a carpule sleeve 30 isdetachably fastened to a distal end of the housing sleeve 20 by abayonet connection, which is described in further detail below. Thisreceives a receptacle in the form of a carpule 40 with a fluidmedicament, in which a stopper 41 is displaceably guided. A medicamentreservoir R of changeable volume is thereby delimited inside thecarpule. Instead of a carpule, a different receptacle can also bepresent, the volume of which is changeable, e.g., a receptacle withwalls folded in a concertina-like manner in the manner of a bellows. Thecontent of the carpule 40 may be monitored through an elongated viewingwindow 34 in the carpule sleeve 30. A needle holder 31 is screwed on thedistal end of the carpule sleeve 30, which needle holder 31 carries ahollow needle (cannula) 32, serving as injection needle, the proximalend of which projects through a sealing septum into the medicamentreservoir R. A removable needle protection sleeve 33 surrounds theforwardly projecting region of the needle 32 and protects a user frombeing pricked accidentally. A protective sleeve 10, the distal end ofwhich is permanently closed by a protective cap 50, is pushed over thecarpule sleeve 30. A holding ring 11 with detent arms 12 extending inthe proximal direction is mounted inside the protective sleeve 10. Theends of the detent arms 12 are detachably engaged with the carpulesleeve 30. The proposed embodiments are described here by an injectiondevice which has a needle 32, but it is also conceivable that theinjection device has several needles or no needle, as in a jet injector.

At the proximal end of the housing sleeve 20, a dosing sleeve 60 isrotatably arranged with a push button 80 held therein. The dosing sleeveserves for the setting of a dose, which is to be distributed from themedicament reservoir R, and for the tensioning of a drive arrangementwith a drive element in the form of a spiral spring 310, acting as atorsion spring. The set dose is displayed on a display drum 70, and canbe read through a window 21 in the housing sleeve 20, which is coveredby a transparent covering 22. A correcting (reduction) of the set dosemay be possible by turning back the dosing sleeve 60, which is describedin further detail below.

With reference to these parts, the following directions can be defined,which will be referred to consistently below: The distal (forward)direction is the direction in which the administering takes place, i.e.,it points along the longitudinal axis from the push button 80 in thedirection of the hollow needle 32. The proximal (rearward) direction isaccordingly defined as the opposite direction. If reference is made to adirection of rotation (clockwise, anticlockwise), this means thedirection of rotation which one observes when one views along thelongitudinal axis in the distal direction.

After the setting of the dose, the hollow needle 32 is pierced throughthe skin of the patient, and a distribution of the dose is triggered bythe user pushing the push button 80 into the dosing sleeve 60. A rotarymovement is produced by the drive arrangement via a mechanism, which isdescribed in detail below, this rotary movement being converted into anadvancing of a delivery element in the form of a thrust sleeve 90 in thedistal direction. The thrust sleeve 90 pushes the stopper 41 of themedicament carpule 40 by the set amount in the distal direction via athrust flange 100 arranged at its distal end, whereby the distributionof the medicament is brought about out of the reservoir R. The thrustsleeve 90 therefore acts as a piston rod for the piston which is formedby the thrust flange 100 and the stopper 41. After the end of theadministering, the user releases the push button 80 again. During theadvance of the thrust sleeve 90, the display drum is entrained by thedrive arrangement such that it returns to its zero position in thecourse of the distribution. The injection pen is thereby immediatelyready for the next dose setting.

When the medicament or therapeutic substance in the medicament reservoirR is running low, i.e. the thrust sleeve 90 is almost completelyextended, this is detected by a dose limiting arrangement in theinjection pen, which is described in further detail below. The doselimiting arrangement allows the user to set as a maximum the remainingavailable residual dose. In a subsequent carpule or ampuole change, thedose limiting arrangement and also the display drum 70 automaticallyreturn into the initial state, and manual resetting may be unnecessary.

The structure and mode of operation of the mechanism are described indetail below.

FIG. 3 shows an enlarged illustration of the rear (proximal) region ofthe injection device of FIG. 1A. The structure of this region will nowbe described in detail substantially from the interior outwardly.

The thrust sleeve 90 is mounted in a guide sleeve 110, arranged suchthat it is locked against relative rotation with respect to the housingand displaceably, locked against relative rotation and displaceably inthe longitudinal direction. For this, the thrust sleeve 90 has, at itsproximal end, several radially outwardly projecting guide cams 91, whichare guided in longitudinal grooves, complementary thereto, on the innerside of the guide sleeve 110.

The guide sleeve 110 can be seen in FIG. 4, which illustrates thecooperation of the guide sleeve 110 with further parts. The guide sleeve110 has at its distal end a radially outwardly projecting,circumferential ring flange 111 with radial bores 112. A ring-shapedbearing holder 130 is pushed from the proximal side via the guide sleeve110, surrounds the ring flange 111 radially and is connected rigidlytherewith via radial cylinder pins, which are not illustrated in thedrawings.

A coupling sleeve 120 is rotatably mounted between the ring flange 111of the guide sleeve 110 and an inwardly projecting shoulder 132 of thebearing holder 130. As is described in further detail below, thecoupling sleeve 120 is connected via a threaded rod 180 with the thrustsleeve 90 and therefore forms a part of a delivery arrangement, which isdriven by a rotary movement and brings about a thrust of the deliveryelement in the form of the thrust sleeve. The coupling sleeve 120therefore absorbs considerable axial forces in operation, which aretransmitted via its bearing onto the guide sleeve 110, the bearingholder 130, the mechanism holder 150 and therefore to the housing.

To construct the bearing so as to be low-loss, the bearing includes ballbearings for providing relatively low friction to a rotating unit.Accordingly, a first ball bearing ring 140 is provided between theflange 111 of the guide sleeve and a radially encircling flange 124 ofthe coupling sleeve 120. A further such ball bearing ring 140 isarranged between the flange 124 and an end face of the bearing holder130.

The ball bearing ring 140 is illustrated in detail in FIGS. 5A and 5B.It carries a plurality of bearing balls 141, i.e., twelve, but mayinclude a range of bearing balls such as from 3 to 24. The bearing balls141 run or roll, as can be seen in FIG. 3, in flat, circular groovesformed in both end faces of the radial flange 124 of the coupling sleeve120, in the corresponding end face of the flange 111 of the guide sleeve110 and in the end face of the bearing holder 130.

The coupling sleeve 120 is illustrated in FIG. 6, together with the ballbearing rings 140 (but without balls 141). On the cylindrical sleevebody 121, a plurality of longitudinal ribs 122 are formed, which extendover a considerable part of the length of the sleeve body in alongitudinal direction up to its proximal end. Corresponding grooves areprovided therebetween. From a thickening area 123, the flange 124follows towards the front, which adjoins the ball bearing rings 140 onboth sides.

FIG. 7 illustrates how the unit of guide sleeve 110 and bearing holder130 is held in a sleeve-shaped mechanism holder 150, so as to be lockedagainst relative rotation, but displaceably arranged in the longitudinaldirection.

The mechanism holder 150 includes a distal section 151 with increasedinternal and external diameter and a proximal section 152 with asomewhat smaller internal and external diameter. These two sections areconnected by a step 153. The outer side of the distal section 151 isheld rigidly in the housing sleeve 20. Thereby, the mechanism holder 150may be immovable with respect to the housing, therefore formingfunctionally a part of the housing.

Adjoining the step 153, at least two longitudinal slits 154 are formedin the mechanism holder 150. Pins, which are not illustrated in FIG. 7,are inserted in the bearing holder 130. These project radially beyondthe bearing holder 130 and into the longitudinal slits 154 of themechanism holder. The bearing holder 130 and the guide sleeve 110, whichis securely connected therewith, may thus be guided displaceably betweena distal and a proximal final position and so as to be secured withregard to rotation in the mechanism holder 150. Toward the proximal end,on the outer covering surface of the mechanism holder 150, an externalthread 157 is formed. Several longitudinal grooves 158 are formed inthis region on the inner surface.

In the distal direction, a bayonet sleeve 160 adjoins the guide sleeve110 and the bearing holder 130, which is also illustrated in FIG. 8. Itis held on the bearing holder 130 in the axial direction and isrotatable with respect thereto. With an inwardly projecting ring flange161, the bayonet sleeve 160 supports the unit of guide sleeve 110 andbearing holder 130, with coupling sleeve 120 held therein, in the distaldirection. The bayonet sleeve 160 has two arms 162 projecting axially inthe distal direction and lying diametrically opposite each other, whicharms 162 have radial openings 163. Radially outwardly projecting pinsare inserted into these openings, which pins run in two guide slits 155of the mechanism holder 150 acting as connecting link guides (positiveguides). Guide slits 155 are configured so that the bayonet sleeve 160,with an anticlockwise rotation (in the sense of the definition indicatedabove, i.e., on observation along the longitudinal axis in the distaldirection) is compulsorily also moved axially in the proximal direction.In this way, the unit of guide sleeve 110, bearing holder 130 andcoupling sleeve 120 is moved in the proximal direction. Vice versa, witha rotation of the bayonet sleeve 160 clockwise, this unit moves in thedistal direction. Parallel to the guide slits 155, a further pair ofguide slits 156 runs, in order to receive radial pins 36 of a lockingregion 35 of the carpule sleeve 30 (cf. FIGS. 1 and 3). On introductionof the carpule sleeve 30 into the housing, the carpule sleeve is alsosubject to a positive guidance, so that the carpule sleeve 30 performs acombined rotary movement and displacement. The carpule sleeve 30 isconfigured such that, upon its movement, it is coupled with the arms 162of the bayonet sleeve 160 and entrains the bayonet sleeve 160.

The guide slits 155 are of finite length and delimit the movement of thebayonet sleeve between a distal and a proximal final position. In FIG.7, the proximal final position is illustrated in which the guide slits155 allow a rotation of the bayonet sleeve through 90 degrees betweenthese positions.

To fix the bayonet sleeve detachably in its two final positions so as tobe locked against relative rotation with respect to the guide sleeve110, and thus with respect to the housing sleeve 20, a bayonet spring170 is arranged between the bayonet sleeve 160 and the guide sleeve 110.This is illustrated, in detail, in FIGS. 9A to 9C. The bayonet spring170 has a substantially flat and ring-shaped base body 171 acting as aspring element. Two diametrically opposite, axially flatly projectingbulges or projections 172 protrude out from this base body as detentelements or detent cams axially in the distal direction. Twodiametrically opposite flat tongues 173 protrude inwardly and come tolie in corresponding flat recesses of the guide sleeve 110. Thereby, thebayonet spring 170 is held, so as to be secured with regard to torsion,on the guide sleeve 110. As can be seen from FIG. 9B, the base body 171is bent slightly about an axis perpendicular to the longitudinal axis,and namely such that the curvature mid-point lies on the same side ofthe bayonet spring as the projections 172 (i.e., distal). As a result,the bayonet spring 170 is pre-stressed between the guide sleeve 110 andthe bayonet sleeve 160 permanently such that the projections 172 arepressed in the distal direction against the correspondingcounter-surface on the ring flange 161. In this counter-surface, fourdepressions are present, which are arranged at intervals of 90 degreesabout the longitudinal axis. In the proximal final position, theprojections 172 come to lie in a first pair of these depressions,whereas in the distal final position, in which the bayonet sleeve isturned through 90 degrees, they are held in the second pair of thedepressions. Thereby, two defined detent positions are provided, inwhich the bayonet sleeve 160 engages via the bayonet spring 170 with theprojections 172 detachably with the guide sleeve 110. In both positions,a certain force may need to be overcome to move the bayonet sleeve inthe direction of the respective other final position again. Each of thedepression pairs may comprise a different configuration, e.g., depthand/or shape, so that a different releasing force is necessary in thetwo detent positions.

In one detent position, the carpule sleeve 30 is held via its couplingwith the bayonet sleeve 160 to be secure with regard to rotation anddisplacement on the guide sleeve 110, and thus on the housing. In theother detent position, the carpule sleeve 30 is detached from thehousing. In this position, the bayonet sleeve 160 is again engaged withthe guide sleeve 110 and is thereby fixed on the housing 20 so as to besecure with regard to rotation and displacement. In this way, thecarpule sleeve, on insertion into the guide slits 156, locates the arms162 of the bayonet sleeve in the correct position around thelongitudinal axis, and can entrain these upon the releasing of thedetent connection.

In the present example, the detent elements are constructed asprojections 172 integrally formed with the spring element in the form ofthe base body 171. Alternatively, a separate detent element may beprovided, e.g., in the form of a rigid ring with detent cams, which maybe pressed in the axial direction by the spring element. As an alternateto projections, the detent element may also have depressions, which thencooperate with corresponding projections of the counter surface. In thepresent example, the detent element is locked against relative rotationwith respect to the housing. Alternatively, it can also be lockedagainst relative rotation with respect to the bayonet sleeve. The springelement may also have an alternative configuration to produce an axialforce. Accordingly, various modifications of locking between the carpulesleeve 30 and the housing are contemplated.

In FIG. 10, the parts of the injection device illustrated in FIG. 7 areillustrated together with the thrust sleeve 90 arranged in the guidesleeve 110. At its proximal end, the thrust sleeve 90 has a shortinternal thread 92 in which a hollow external threaded rod 180 isguided. The latter is connected at its proximal end rigidly with thecoupling sleeve 120 via a transverse pin 181. A thrust of the thrustsleeve 90 in the distal direction takes place, by the coupling sleeve120, which is rotatably mounted, carrying out a rotary movement. As aresult of the rigid connection between coupling sleeve 120 and externalthreaded rod 180, this rotary movement also brings about a rotation ofthe external threaded rod 180. The thrust sleeve 90 runs with itsinternal thread 92 on the external threaded rod 180, similar to a nut.The thrust sleeve 90 is locked against relative rotation with respect tothe guide sleeve 110, because it runs via the guide cams 91 inlongitudinal grooves on the inner side of the guide sleeve 110. In thisway, the thrust sleeve 90 is advanced axially on a rotation of theexternal threaded rod 180. Accordingly, a rotary movement of thecoupling sleeve 120 is converted into an axial displacement of thethrust sleeve 90.

As can be seen from FIG. 3, the thrust sleeve 90 is assisted in thisthrust movement by a long helical spring 190, which is subjected topressure, and which is arranged in the interior of the threaded rod 180and is guided on a guide needle 200. The helical spring 190 presses aring-shaped thickening 201 close to the distal end of the guide needle200 in the distal direction against the thrust flange 100. An axial pin202 projects into a corresponding blind-end bore of the thrust flange100 and is rotatable in this blind-end bore.

Furthermore, in FIG. 10 a substantially cylindrical transmission sleeve210 is inserted into the mechanism holder 150 from the proximal side,which transmission sleeve partially surrounds the coupling sleeve 120.The transmission sleeve 210 has on the outer side a plurality oflongitudinal ribs 212. The external diameter of the transmission sleeve210 is selected here so that, despite its external longitudinal ribs, itis freely rotatable inside the mechanism holder 150. On the inner side,the transmission sleeve 210 has an internal thread 211, in which a doselimiting ring 220 runs with a corresponding external thread 221. In theinterior of the dose limiting ring 220, longitudinal grooves 222 arepresent which can be seen in FIGS. 12A and 12B, into which thelongitudinal ribs 122 of the coupling sleeve 120 (cf. FIG. 6) engage.Thereby, the dose limiting ring 220 is movable on the one hand so as tobe secure with regard to rotation in the axial direction on the couplingsleeve, and on the other hand is guided in the internal thread of thetransmission sleeve 210. A rotation of the coupling sleeve 120 withrespect to the transmission sleeve 210 therefore leads to a rotation andaxial displacement of the dose limiting ring 220.

The axial displacement range of the dose limiting ring is limited in thedistal and proximal directions. This is described in conjunction withFIGS. 11A, 11B, 12A and 12B.

In FIGS. 11A and 11B, a coupling shaft 230 is connected with thetransmission sleeve 210. The coupling shaft comprises an axis 231 with atransverse bore 232 close to the proximal end 233. A circumferentialflange 234 extends radially outwardly from the distal end of the axis. Aring flange 235 extends in turn therefrom axially in the distaldirection. The external diameter of the circumferential flange 234 isgreater than that of the ring flange 235, whereby the circumferentialflange 234 protrudes radially over the ring flange 235, and forms a stopfor the transmission sleeve 210. The ring flange 235 is pushed into thetransmission sleeve 210, so that the latter lies with its proximal endagainst the circumferential flange 234. The ring flange is secured byradial pins in the transmission sleeve 210, which are pushed into bores237. Thereby, the coupling shaft 230 and the transmission sleeve 210 areconnected with each other so as to be locked against relative rotationand secured against displacement. Several longitudinal grooves 238 areformed in the inner surface of the ring flange 235.

FIGS. 12A and 12B show the coupling shaft 230 and the dose limiting ring220 alone. A radial stop 223, which cooperates with a correspondingradial stop 236 on the ring flange 235 of the coupling shaft, is formedon the dose limiting ring 220. A radial stop is understood to mean astop surface, the surface normal of which points substantially in thetangential direction, and which is formed to cooperate with acorresponding counter surface. The radial stop is therefore primarilystressed in a tangential direction (i.e., in a rotational direction)instead of in an axial direction. Thereby, a radial stop avoids the riskof jamming, such as when two parts collide axially via a screwconnection, e.g., in the case of a small pitch of the helical thread.The radial stop 236 delimits the screw motion of the dose limiting ring220 in the proximal direction. In FIG. 11A the dose limiting ring 220 isshown in the resulting proximal final position, and in FIG. 11B on theother hand in a distal initial position.

The proximal end of an arresting sleeve 280 is rotatably clicked into aninwardly directed ring flange 213, chamfered in the distal direction, atthe distal end of the transmission sleeve 210. For better clarity, thearresting sleeve 280 is not illustrated in FIG. 10. However, it is shownin FIG. 13. The arresting sleeve comprises a ring-shaped main body 281,from which four arms 282 extend in the distal direction. On its innersurface, the main body has longitudinal grooves 284, which are meshedwith the longitudinal ribs 122 of the coupling sleeve 120. Thereby, thearresting sleeve 280 is displaceable in the longitudinal directionrelative to the coupling sleeve 120, but is secured as regards torsionwith respect thereto. At the end of the arms 282, inwardly extendingflange regions 283 are present. The possible displacement range islimited in the proximal direction by these flange regions. These abut inthe proximal final position of the arresting sleeve 280, as illustratedin FIG. 3, onto the distal end of the longitudinal ribs 122 of thecoupling sleeve 120. Longitudinal ribs are formed on the outerperipheral surface of the main body 281. These longitudinal ribs engage,in the position of FIG. 3, into the inner longitudinal grooves 158 ofthe mechanism holder 150. Thereby, the arresting sleeve 280 isdisplaceable in this position axially with respect to the mechanismholder 150, but secured with regard to torsion. The arresting sleeve 280in this position therefore secures the coupling sleeve 120 against arotation in the mechanism holder 150. As described further below, thearresting sleeve 280 is, however, displaceable so far in the distaldirection that it can come out of engagement with the mechanism holder150 and is then rotatable with the coupling sleeve 120.

The arresting sleeve 280 is pre-stressed in the proximal direction by acoupling spring 290. The coupling spring is configured as a helicalspring, which is subjected to pressure, surrounds the arms 282 of thearresting sleeve 280 and lies with its proximal end against the distalend face of the main body 281. At the distal end of the coupling spring290, the latter is held on a support ring 300, which abuts against thebearing holder 130 in the distal direction and on the inner side ofwhich longitudinal grooves are formed.

In FIG. 14, the unit of FIG. 10 is illustrated with further components.The display drum 70 is held on the mechanism holder 150. In addition, astop sleeve 240 is connected immovably with the housing sleeve 20 bypins projecting into the radial holes 242, e.g., see FIG. 14. At thedistal end of stop sleeve 240, radial stops 243 are provided, and at theproximal end, teeth 244, e.g., serrated teeth, are arranged on the endface for a ratchet connection, described below.

The display drum 70 has an internal thread, which can be seen in FIG. 3,and runs on the external thread 157 of the mechanism holder, which canbe seen in FIGS. 7 and 10. At its proximal end, the display drum 70narrows to a ring-shaped region 72. Longitudinal grooves are formed onthe inner side of the ring-shaped region 72. By these longitudinalgrooves, the display drum 70 is secured with regard to torsion, but isguided displaceably in the longitudinal direction on the longitudinalribs 212 of the transmission sleeve 210. Through the combination of thislongitudinal guide on the transmission sleeve and the thread guide onthe mechanism holder, a rotation of the transmission sleeve 210 leads toa combined rotation and longitudinal displacement of the display drum70. This movement is delimited or stopped by radial stops in bothdirections. At the proximal end, a radial stop cooperates with theradial stop 243 of the stop sleeve 240. At the distal end, acorresponding radial stop 73 cooperates with a radial stop 159 of themechanism holder 150. Thereby, the screw motion of the display drum 70is limited in both directions by radial stops.

The mechanism for setting a dose and for triggering its administering isdescribed with reference to FIGS. 3 and 15. The dosing sleeve 60 isarranged at the proximal end of the housing sleeve 20. Dosing sleeve 60is secured with regard to displacement axially with a spring ring 61 andis fixed rotatably on the stop sleeve 240. The dosing sleeve 60 isrotatable via a slip coupling in the form of a ratchet connection bothclockwise and also anticlockwise about the longitudinal axis towards thehousing sleeve 20, and is thus configured and arranged to assume severalpredefined detent positions.

The dose setting mechanism comprises an inner ring 250 arranged insidethe dosing sleeve 60 and rigidly connected with the dosing sleeve 60.The inner ring 250 has in its radial inner surface a plurality oflongitudinal grooves. In the distal direction from the inner ring 250, aratchet ring 260 is held axially displaceably but secured with regard torotation in the dosing sleeve 60. The ratchet ring 260 is serrated onits distal end face, and namely in a complementary manner to the teeth244 of the serrated proximal end face of the stop sleeve 240, so thatteeth of the ratchet ring 260 can engage in depressions on the end faceof the stop sleeve 240 and vice versa. The ratchet ring 260 is axiallydisplaceable by a certain amount between the distal end face of theinner ring 250 and the serrated proximal end face of the stop sleeve240. The amount by which an axial displacement is such that the serratedend faces of the ratchet ring 260 and of the stop sleeve 240 can comeout of engagement. The ratchet ring 260 is pressed elastically by anelastic force against the stop sleeve 240. For this, several axial bores251 are present in the form of blind-end bores in the inner ring 250.Helical springs 252, which are subjected to pressure are inserted in atleast one of these bores, e.g., in at least two bores, at a uniformspacing along the circumference of the ring when multiple bores areprovided. The helical springs 252 press the ratchet ring elasticallyagainst the stop sleeve.

In the position of rest, the ratchet ring 260, with its serrated endface, is in engagement with the serrated end face of the stop sleeve240. Thereby, the ratchet ring and the dosing sleeve 60 connectedtherewith assume one of several defined angle positions about thelongitudinal axis. With a rotation of the dosing sleeve 60 relative tothe housing sleeve 20, the teeth of the ratchet ring 260 and of the stopsleeve 240 slide on each other against the axial spring force of thehelical springs 252, until they come out of engagement and arrive inengagement again in the next defined angle position. In this way, anelastically detachable detent connection is produced by rotation with asufficient torque in several predefined angle positions of the dosingsleeve 60 relative to the housing sleeve 20. This mechanism can also bedesignated as a double slip coupling.

By rotation of the dosing sleeve 60 clockwise, the spiral spring 310 canbe tensioned, which is indicated in FIG. 3. The spiral spring 310 has aplurality of spring coils, which run around the longitudinal axis andare arranged over one another radially to the longitudinal axis. Theinner end of the spiral spring 310 is fastened to a spring holdingregion 311 of the coupling shaft 230, which region can be seen in FIG.12C. The outer end of the spiral spring 310 is mounted on a springsleeve 320, which is held so as to be locked against relative rotationin the stop sleeve 240.

A coupling disc 270 is mounted on the coupling shaft 230, and is securedagainst rotation and displacement by a pin 271 in the transverse bore232 of the coupling shaft 230. The coupling disc 270 has a plurality oflongitudinal ribs on its outer peripheral surface. In the position ofFIG. 3, these longitudinal ribs engage into the longitudinal grooves,which are complementary, on the inner side of the inner ring 250, butcan be brought out of engagement by an axial displacement.

The dosing sleeve 60 has an axial passage opening, in which the pushbutton 80 is arranged so as to be axially displaceable. The push button80 is rotatable with a plurality of radially elastic arms 81 and isclicked on the proximal end 233 of the coupling shaft 230 so as to besecured against displacement. It abuts with its distal end against aproximal end face of the coupling disc 270. In the interior of the pushbutton 80 there is a helical spring 82, which lies with its proximal endagainst the inner end face of the push button and presses with itsdistal end against a bearing ring 83. The bearing ring 83 has on itsouter peripheral face longitudinal ribs, which are guided incorresponding longitudinal grooves in the inner covering surface of thepush button 80. Thereby, the support ring 83 is arranged in the pushbutton 80 so as to be locked against relative rotation and so as to beaxially displaceable. The bearing ring 83 is configured be serrated in aflat manner on its distal end face. The proximal end face of thecoupling disc 270 is formed so as to be serrated in a complementarymanner hereto, so that the bearing ring 83 is axially meshed with thecoupling disc 270. On distribution of the medicament, the coupling disc270 rotates with respect to the bearing ring 83. Thereby, the serratedsurfaces slide on one another, so that the toothing comes alternatelyinto and out of engagement. Thereby, a characteristic clicking sound isproduced, which indicates to the user that an administering is justtaking place. The toothing of bearing ring 83 and coupling disc 270 maybe configured so that each clicking corresponds to one unit, or of apredetermined multiple of one unit, of the administered medicament.

The mechanism for setting the dose and the distribution may be arrangedand configured in the housing sleeve 20 so as to be protected againstsplashing, i.e., sealed. According to certain embodiments, four sealsD1, D2, D3 and D4 may be provided. The seal D1 comprises a sealing ring,which lies in a sealing manner between the mechanism holder 150 and thebayonet sleeve 160. The mechanism holder 150 is mounted immovably andtightly in the housing 2, and the bayonet sleeve 160 is bothdisplaceable and rotatable with respect to the mechanism holder 160 andis sealed with respect to the housing by the seal D1.

The seal D2 comprises a further sealing ring, constructed so as to beflat, which lies in a sealing manner between the bayonet sleeve 160 andthe smooth outer side of the thrust sleeve 90. Thrust sleeve 90 may havea smooth (e.g., within accepted and/or manufacturing tolerances) orsubstantially smooth outer wall region, the length of which correspondsat least to the distance between the distal final position and theproximal initial position of its longitudinal movement, between whichthe thrust sleeve 90 is movable in the course of the administering. Thesealing effect between seal D2 and thrust sleeve 90 may be facilitatedby providing an outer wall region of the thrust sleeve 90 with finestructures, e.g. scales, a pattern or texture, in the range below 100micrometres, e.g. below 10 micrometres, and may be configured as micro-or nano-structuring, at least along the length between the distal finalposition and the proximal initial position. A thrust sleeve 90 with suchmicro- or nano-structuring may be considered substantially smooth to oneof skill in the art due to the minute size of the structures. However,one of skill in the relevant art would also appreciate the usefulness ofsuch structures in maintaining and/or enhancing a seal between thethrust sleeve 90 and seal D2. In some embodiments, the outer wall regionmay extend from thrust flange 100 to guide cams 91. In addition, textureor structure provided on the substantially smooth surface may extendalong the entire outer wall region or along portions thereof. Texture 93along the thrust sleeve is depicted in FIG. 1B, which is configured asmicro-structured scales. In addition or alternatively, other structures,such as surface protrusions or indentations, which may have a desiredtexture or structure, may be provided along the outer wall region. Suchadditional or alternative structures may have an orientation such thatthe structures are directed towards the proximal or distal direction.Furthermore, the thrust flange 100 is arranged tightly on the thrustsleeve 90. The region of the injection device, including the interior ofthe thrust sleeve 90, lying proximally from the bayonet sleeve 160, maythus be sealed against the region lying distally. Where fluids areintroduced into this distal region, e.g., due to a breakage of themedicament carpule 40, the fluid may be prevented from penetrating intothe mechanics, thus preventing contamination or jamming.

The other two seals are situated at the proximal end of the injectiondevice. The seal D3 comprises a sealing ring, which lies in a sealingmanner between the dosing sleeve 60 and the stop sleeve 240. The stopsleeve 240 is mounted immovably and tightly in the housing sleeve 20,whereas the dosing sleeve 60 is rotatable with respect to the stopsleeve 240. The seal D4 comprises a further sealing ring, which lies ina sealing manner between the dosing sleeve 60 and the push button 80. Inaddition, a transparent window covering 22 is placed in a fluid-tightmanner on the window 21. Accordingly, mechanisms, operational componentsor mechanics, which are delimited toward the exterior by the housingsleeve 20, the dosing sleeve 60 and the push button 80, are also sealedtoward the exterior and may be protected against the penetration offluids. Rainfall or a glass of water accidentally spilt by the user cantherefore also not harm the injection device.

The seal towards the thrust sleeve may be configured such that it actsas a stripper, similar to a windshield wiper in a car. For this, atleast towards the distal side, there is as small a contact angle betweenthe surfaces of the sealing element and the thrust sleeve, which may liebelow 90 degrees.

Instead of conventional seals or in addition hereto, the parts which areto be sealed with respect to each other may be configured with ahydrophobic surface, such as being formed of or coated with ahydrophobic material. A hydrophobic surface may prevent the parts frombeing wetted. Drops of water thereby roll off and a leaking of fluidsthrough gaps is efficiently prevented between the parts, which are to besealed due to capillary effects. The parts provided with a hydrophobicsurface, which are to be sealed with respect to each other, maytherefore be arranged at a certain distance (gap) from each other,without the sealing effect being lost (“virtual seal”).

A hydrophobic surface is understood here to mean a surface for which thecontact angle of a water drop is at least 90 degrees, e.g., at least 110degrees. The contact angle is the angle between the surface normal ofthe water drop and the respective surface at the contact site. Examplesof materials with hydrophobic characteristics are PTFE(polytetrafluoroethylene) or PVDF (polyvinylidene fluoride), as well asother hydrophobic materials that may be formed as thin coatings, e.g.,in the range of a few micrometres, to provide a hydrophobic surface.

In experiments, various pens and a sleeve were providednanotechnologically with a hydrophobic coating. 20 pens with externaldiameters of 10.0 to 11.9 mm in graduations of 0.1 mm were examined. Thepens were arranged centrally in a sleeve with 12 mm internal diameter,which corresponds to gap thicknesses of 0.05 mm to 1.0 mm in graduationsof 0.05 mm. The interior of the sleeve was then acted upon with water. Asealing effect up to a gap thickness of approximately 0.5 mm wasobserved. With reciprocal rotation between pen and sleeve, a sealingeffect up to a gap thickness of approximately 0.25 mm was observed.

To improve the sealing effect, the surfaces may be micro- ornano-structured, i.e., provided with structures, the dimensions of whichare in the nanometre to micrometre range. These structures can have aselected direction, to inhibit the flow of fluids on the surface in onedirection. Thus, for example, scales can be provided.

The mode of operation of the injection device is now to be describedbelow with reference to FIG. 16, in which an exemplary injection deviceis illustrated in its initial position before the first use. Themechanism described above for setting and distributing a dose has threecouplings K1, K2 and K3 for the transmission of torques. Each of thesecouplings may be brought into and out of engagement by an axial movementof two components with respect to each other.

The coupling K1 is formed by the longitudinal grooves on the innersurface of the axial flange 235 of the coupling shaft 230 as a couplinginput member in cooperation with the longitudinal ribs 122 on the outerside of the coupling sleeve 120 (cf. FIG. 5) as coupling output member.In the position of FIG. 16, this coupling is uncoupled, i.e., thecoupling formed by the cooperation of the longitudinal grooves andlongitudinal ribs is out of engagement. The coupling K1 can be coupledby an axial displacement of the coupling shaft 230 in the distaldirection.

The coupling K2 is formed by the longitudinal grooves in the radialinner surface of the inner ring 250 as a coupling input member incooperation with the longitudinal ribs on the radial outer surface ofthe coupling disc 270 as coupling output member. In the position of FIG.16, this coupling is coupled, i.e., the toothing formed by thelongitudinal grooves and longitudinal ribs is in engagement. Thecoupling K2 can be uncoupled by an axial displacement of the couplingdisc 270 in the distal direction.

The coupling K3 is formed by the longitudinal ribs on the outer side ofthe outer ring flange arms 282 of the arresting sleeve 280 as couplinginput member in cooperation with the longitudinal grooves 158 on theinner surface of the mechanism holder 150 as coupling output member. Inthe position of FIG. 13, this coupling is coupled. It can be uncoupledby an axial displacement of the arresting sleeve 280 in the distaldirection.

All three couplings K1, K2 and K3 can be coupled and respectivelyuncoupled by the push button 80 being displaced axially. On pressing inof the push button 80, the coupling disc 270 and the coupling shaft 230,which is securely connected therewith, are displaced in the distaldirection. In this instance, the coupling K1 comes into engagement,i.e., the coupling shaft is coupled for torque transmission with thecoupling sleeve 120. At the same time, the coupling shaft 230 advancesthe transmission sleeve 210 in the distal direction. This entrains thearresting sleeve 280 in the distal direction, whereby the couplingspring 290 is compressed. When the coupling K1 arrives in engagement forthe first time, the arresting sleeve 280 is not yet advancedsufficiently far to arrive with its outer ring flange arms 282 out ofengagement with the mechanism holder 250. The coupling K3 is thereforeinitially still coupled. The same applies to the coupling K2: Thecoupling disc 270 is still in engagement with the inner ring 250.Therefore, all three couplings are coupled. When the push button 80 ispushed in further, the coupling K2 comes out of engagement. With a stillfurther pushing in, coupling K3 comes out of engagement. Therefore, thecouplings are as follows: Initial state: K1 uncoupled, K2 and K3coupled. Pushing in of the push button 80: K1 couples, thereafter K2uncouples, thereafter K3 uncouples.

FIG. 19, described further below, shows the injection device with thepush button 80 pushed in completely. The coupling K1 is coupled, whereasthe couplings K2 and K3 are uncoupled.

On releasing of the push button 80, the engaging of the couplings intoeach other runs in the reverse sequence. Here, the coupling spring 290presses the arresting sleeve 280, the transmission sleeve 210, thecoupling shaft 230, the coupling disc 270 and the push button 80 backinto the distal initial position.

The couplings K1, K2 and K3 and the ratchet connection make possible thesystematic transmission of torques between five functionally independentunits. A first unit comprises the housing sleeve 20, the mechanismholder 150, the stop sleeve 240 and the spring ring 320. This unit canbe regarded functionally as a holding arrangement or as a housing in anextended sense. It constitutes the stationary reference system for allmovements.

A second unit comprises the dosing sleeve 60, the inner ring 250 and theratchet ring 260. It can be regarded functionally as a rotatable dosingarrangement. This dosing arrangement is held detachably on the housingby the ratchet connection, but so as to be secure with regard to torqueup to a certain value.

A third unit comprises the coupling disc 270, the coupling shaft 230 andthe transmission sleeve 210, which are rigidly connected with eachother, and by the spiral spring 310, connected therewith, which acts asthe actual drive element. This unit can be regarded as a drivearrangement. The rotary movement of the drive arrangement is limited bytwo limiting elements, which are both guided on the transmissionarrangement. The first limiting element is formed by the display drum70, which limits the range of movement of the drive arrangement in bothdirections, a dosing direction and a correction and distributiondirection. The second limiting element is formed by the dose limitingring 220, which limits the range of movement of the drive arrangement atleast in one direction, the dosing direction, independently of the firstlimiting element. The drive arrangement is able to be coupled detachablyby the coupling K2 so as to be locked against relative rotation withrespect to the dosing arrangement, which makes it possible to tensionthe drive element in the form of the spiral spring 310.

A fourth unit comprises the coupling sleeve 120 and the threaded rod180, which form a rigid unit, the elements on which these parts aremounted, namely the guide sleeve 110, the bearing holder 130 and theball bearing rings 140, and also the thrust sleeve 90. This unitconstitutes a delivery arrangement, which converts a rotary movement ofan input member in the form of the coupling sleeve 120 into a thrust ofthe delivery element in the form of the thrust sleeve 90. Its inputmember is able to be detachably coupled by the coupling K1 so as to belocked against relative rotation with the drive arrangement. Inaddition, it is able to be detachably coupled via the coupling K3 so asto be locked against relative rotation with the holding arrangement(i.e., the housing).

Furthermore, a triggering arrangement is present, which comprises thepush button 80 and serves for the operation of the couplings K1 to K3.

The injection device is operated as follows. Starting from the initialposition of FIG. 16, a dose is set, which is to be administered. Forthis, the dosing sleeve 60 is turned clockwise. In so doing, the dosingsleeve entrains the coupling disc 270 and the coupling shaft 230 via thecoupling K2, and the spiral spring 310 is wound up. The torque generatedis held by the ratchet connection between the co-rotating ratchet ring260 and the stationary stop sleeve 240. Through the rotation of thecoupling shaft 230, the transmission sleeve 210 and the display drum 70,which is guided thereon, are also co-rotated. The display drum 70,threadably guided on the mechanism holder 150, is additionally displacedaxially in the proximal direction, and therefore performs as a whole ascrew motion in the proximal direction. Markings on the surface of thedisplay drum 70 pass through under the window 21 and indicate the setdose. Furthermore, the dose limiting ring 220, threadably engaged withthe interior of the transmission sleeve 210 and arranged, secured withregard to rotation, on the coupling sleeve 120, is displaced in theproximal direction.

FIG. 17 shows the injection device after half the maximum individualdose has been set. The display drum has traveled rearwardly half-waybetween its distal (forward) and its proximal (rear) final position. Inaddition, the dose limiting ring 220 has traveled in the proximaldirection by an amount proportional to the individual dose that has beenset.

The rotation of the dosing sleeve 60 clockwise is limited, on the onehand, by the maximum movement range of the display drum 70, and on theother hand, by the maximum movement range of the dose limiting ring 220.After a predetermined number of revolutions of the dosing sleeve 60, thedisplay drum 70 abuts with its proximal radial stop against the stopsleeve 240, in so far as the rotation of the dosing sleeve 60 has notbeen previously limited by the dose limiting ring 220, as is describedfurther below. Thereby, no further rotation of the dosing sleeve 60 ispossible. This position corresponds to the maximum individual dose,which can be set. This situation is illustrated in FIG. 18.

If the set dose is to be corrected, i.e., reduced, then the dosingsleeve 60 can be turned back anticlockwise against the force of theratchet connection. As the ratchet connection in this direction absorbsthe torque of the spiral spring 310, the ratchet connection isconfigured asymmetrically: The toothing on the end face has a largerangle of inclination on the side which is stressed by a torque whichacts anticlockwise onto the dosing sleeve than on the side which isstressed with a torque clockwise (cf. the configuration of the teeth 244in FIG. 14). The angle of inclination is understood here to mean theabsolute amount of the angle between the respective flank of a tooth onthe end face of the ratchet ring 260 or on the end face of the stopsleeve 240 and a cross-sectional area through the injector.

The distribution or delivery of the dose, which has been set is actuatedor initiated by the push button 80 being pushed in. In this instance,the coupling K1 is coupled, and a connection is produced which is lockedagainst relative rotation between the coupling shaft 230, on the onehand, and the coupling sleeve 120 and also the threaded rod 180 rigidlyconnected therewith, on the other hand. All three couplings K1, K2 andK3 are coupled. On further pushing in of the push button 80, thecoupling K2 uncouples. Thereby, the connection, which is locked againstrelative rotation between the dosing sleeve 60, on the one hand, and thecoupling shaft 230 with the coupled coupling sleeve 120 and threaded rod180, on the other hand, is cancelled. This leads to the ratchetconnection no longer absorbing the torque of the spiral spring 310.However, the system is held so as to be locked against relative rotationvia the coupling K2 in the mechanism holder 150 and hence in the housingsleeve 20. When the push button 80 is pressed further, the coupling K3also uncouples. At this moment, the torque of the spiral spring 310becomes free and acts via the coupling shaft 230 and the coupling sleeve120 on the threaded rod 190. Hereby, these parts are set in ananticlockwise rotation. Through its thread engagement with the threadedrod 190, the thrust sleeve 90 undergoes an axial displacement in thedistal direction. Via the thrust flange 100, the thrust sleeve advancesthe stopper 41 in the carpule 40. In this way, the medicament isdistributed or injected.

During the distribution or injection process, axial forces act on thethrust sleeve 90: The torque of the spiral spring 310 is converted intoa force in the thrust direction, which advances the stopper 41 in thecarpule 40. These forces are absorbed by the ball bearings between thecoupling sleeve 12 and the guide sleeve 110 and the bearing holder 130,in a low-friction manner, so that counter forces (i.e., frictionalcounter forces), which could reduce the driving torque, are minimized.

In the distribution, the display drum 70 is entrained by the rotation ofthe transmission sleeve 210 anticlockwise and is moved in the distaldirection due to its engagement with the stationary mechanism holder150, until it assumes its distal initial position. In this position, itis prevented from rotating further by a radial stop, whereby thedistribution is terminated. After the end of the distribution, thedisplay drum 70 indicates the dose “zero”.

The distribution can be interrupted at any time by the push button 80being released. Thereby, the couplings K3 and K2 couple again, and thecoupling K1 uncouples again. The display drum 70 indicates the remainingresidual dose which is further distributed when the push button ispressed again and thereby the distribution is continued.

The dose limiting ring 220 maintains its axial position during thedistribution, because the transmission sleeve 210 and the couplingsleeve 120, between which the dose limiting ring 220 is situated, rotatesynchronically.

After the end of the distribution, the injection device is ready for thenext injection process. Compared with FIG. 16, however, two componentshave changed their position: On the one hand, the thrust sleeve 90 hastraveled in accordance with the distributed dose in the distaldirection. On the other hand, the dose limiting ring 220 has likewisetraveled by an amount proportional thereto in the proximal direction.Apart from this, the state after the end of the injection corresponds tothe initial state of FIG. 16. With each further injection, the thrustsleeve 90 therefore travels further in the distal direction, whereas thedose limiting ring 220 travels in the proximal direction. This isillustrated in FIG. 19, which illustrates the injection device after afirst dose is administered, which corresponds to half the maximumindividual dose, and then with the dosing sleeve a dose was again set,which in turn corresponds to half the maximum individual dose. Thedisplay drum indicates, as in FIG. 15, half the maximum individual dose,whereas the dose limiting ring 220 assumes a position in thetransmission sleeve 210, which corresponds to the sum of the doses whichhave been set, e.g., twice half the maximum individual dose.

The maximum axial path by which the dose limiting ring 220 can travel inthe proximal direction in the transmission sleeve corresponds to thecontent of a completely filled carpule. As soon as the sum of the dosesset on the dosing sleeve corresponds to the carpule content, the doselimiting ring 220 reaches its proximal final position and abuts with itsradial stop against the axial ring flange 235 of the coupling shaft 230,as is illustrated in FIG. 12A. Thereby, the dosing sleeve 60 isprevented from a further clockwise rotation, and no larger dose can beset than the dose corresponding to the remaining residual amount of themedicament in the carpule. FIG. 20 shows this situation, in which nofurther increasing of the dose is possible, although the display drum issituated in the distal initial position, i.e., the zero position.Correspondingly, the thrust sleeve 90 has reached its maximum, distalfinal position.

To exchange the carpule, the carpule sleeve 30 is detached from themechanism holder 150 against the elastic resistance of the bayonetspring 170, and is unscrewed, guided through the corresponding guideslit 156 in the mechanism holder. Compulsorily, the bayonet sleeve 160is twisted along its own, parallel guide slit 155, and is displaced inthe distal direction. The guide sleeve 110 is drawn in the distaldirection, and the movable parts, which are connected axially therewith,also travel in the distal direction, including the coupling sleeve 120,the threaded rod 190, the arresting sleeve 280, the transmission sleeve210, the coupling shaft 230, the coupling disc 270 and the push button80. The push button 80 is therefore drawn into the dosing sleeve 60 andthus indicates that the injection device is not ready for operation.

Through this axial displacement of the various parts of the mechanism,the couplings K2 and K3 come out of engagement, while K1 is already outof engagement. If a dose had still been set before the carpule change,but had not been administered, the wound spiral spring 310 sets thecoupling shaft 230 and the transmission sleeve 210 connected therewithinto an anticlockwise rotation, until the display drum 70 has reachedits distal final position and prevents a further turning back by itsradial stop on the mechanism holder 150. In this way, the display drum70 is brought back into its distal initial position, the zero position.An automatic resetting of the dose display to zero therefore takesplace.

If, before the carpule change, a residual amount of the medicament wasstill situated in the carpule 40, then the thrust sleeve 90 had not yetmoved out to a maximum before the carpule change, and had therefore notyet reached its distal final position. On removal of the carpule sleeve30, the helical spring 190 presses the guide needle 200, the thrustflange 100 and the thrust sleeve 90 in the distal direction. Thus, thethreaded rod 180 is set in rotation via its screw connection with theinterior of the thrust sleeve 90. The threaded rod 180 entrains thecoupling sleeve 120 and the dose limiting ring 220. With this rotation,the dose limiting ring 220 is displaced into its proximal final positionthrough its thread engagement with the transmission sleeve 210. As soonas the dose limiting ring 220 has reached this initial position, itprevents a further rotation of the coupling sleeve 120 and of thethreaded rod 180, so that no further moving out of the thrust sleeve 90is possible, and the thrust sleeve 90 has reached its distal finalposition, as illustrated in FIG. 1A. In addition, the display drum 70 issituated in the zero position, the dose limiting ring 220 in theproximal final position and the thrust sleeve 90 in its distal finalposition.

A new carpule 40 may be pushed into the carpule sleeve 30, and thecarpule sleeve 30 with the carpule 40 held therein may be guided axiallyin the proximal direction against the housing sleeve 20. In thisposition, the stopper 41 of the carpule presses the thrust flange 100and the thrust sleeve 90 against the force of the helical spring 190 inthe proximal direction. As a result, the threaded rod 180 is set inrotation. The threaded rod entrains the coupling sleeve 120 and the doselimiting ring 220. The dose limiting ring, threadably engaged with thetransmission sleeve 210, is displaced in the distal direction, i.e., inthe direction of its initial position. The degree of displacement inthis direction corresponds to the dose present in the carpule 40. With acompletely filled carpule, the dose limiting ring 220 travels into itsdistal initial position. The carpule sleeve 30 is then pushed into themechanism holder 150, with the radial pins 36 of the carpule sleeve 30engaging again into the guide slits 156 in the mechanism holder 150 (cf.FIGS. 1 and 3). Through the positive guidance of the carpule sleeve 30on insertion into the mechanism holder 150, the bayonet sleeve 160 isforced to follow the movement of the carpule sleeve 30 in thecorresponding guide slits. The bayonet sleeve 160 is thereby broughtback into its proximal final position, in which it is detachably lockedby the bayonet disc 170 (cf. FIGS. 8 to 10). The injection device isthus situated in the initial position of FIG. 16 and, after the screwingof a new needle holder 31, is available for a new sequence ofadministrations.

In FIG. 21, another exemplary embodiment of an injection deviceaccording to the present invention is illustrated as a variant. The modeof operation is substantially the same as in the first embodimentdescribed above. Parts which perform similarly are therefore designatedby the same reference numbers as in the first embodiment, thedifferences of the second embodiment being described below.

In the second embodiment, the stop sleeve 240 is omitted. Rather, itsfunction is taken over by the correspondingly extended housing sleeve20.

The drive arrangement which, in the first embodiment, apart from thespiral spring 310, is formed from the coupling disc 270, coupling shaft230 and transmission sleeve 210, is formed in the second embodiment bydifferent parts, including a connecting shaft 400 (with coupling disc401 formed integrally thereon), a first transmission sleeve 410 closedat the proximal end, and a second transmission sleeve 420 adjoiningdistally thereto. These three parts are, in turn, connected rigidly witheach other.

Whereas in the first embodiment, the display drum served to indicate theset dose and to delimit the maximum individual dose which was able to beset in the dosing direction and to delimit the movement in thedistribution direction, the latter function in the second embodiment istaken over by a second dose limiting ring 430. The latter is guided soas to be locked against relative rotation, but axially displaceable, inthe housing sleeve 20. With an internal thread it runs on acorresponding external thread of the first transmission sleeve 410. Itsaxial movement is limited by two radial stops between a distal initialposition, which corresponds to the zero position, and a proximal finalposition, which corresponds to the maximum dose which is able to be set.In this way, it takes over the stop functions of the display drumaccording to the first embodiment.

The display drum 70 in the second embodiment is guided axiallydisplaceably via a carrier sleeve 440, rigidly connected therewith, andso as to be locked against relative rotation on the second transmissionsleeve 420. Its mode of operation is otherwise identical to the firstembodiment.

Apart from these differences, the structure and mode of operation of theinjection device are substantially the same as in the first embodiment.

The differences between the first and the second embodiment show thatthe functions of an injection device according to the present inventioncan be reached in a variety of ways and the invention is in no wayrestricted to the exemplary embodiments. Various further modificationsare possible, which may be due to manufacturing requirements.

Embodiments of the present invention, including preferred embodiments,have been presented for the purpose of illustration and description.They are not intended to be exhaustive or to limit the invention to theprecise forms and steps disclosed. The embodiments were chosen anddescribed to provide the best illustration of the principles of theinvention and the practical application thereof, and to enable one ofordinary skill in the art to utilize the invention in variousembodiments and with various modifications as are suited to theparticular use contemplated. All such modifications and variations arewithin the scope of the invention as determined by the appended claimswhen interpreted in accordance with the breadth they are fairly,legally, and equitably entitled.

1. A device for the administering of a fluid product, comprising ahousing, a reservoir and a delivery element for delivering the productfrom a reservoir, wherein the delivery element extends from the interiorof the housing and is movable relative to the housing, wherein thedelivery element is guided in a fluid-tight manner with respect to thehousing.
 2. The device according to claim 1, wherein the deliveryelement is movable along a thrust axis between a proximal initialposition and a distal final position and has a substantially smooth,cylindrical outer wall region, the length of which corresponds at leastto the distance between the distal final position and the proximalinitial position, and wherein the cylindrical outer wall region issurrounded by at least one ring-shaped sealing element.
 3. The deviceaccording to claim 2, wherein the at least one ring-shaped sealingelement comprises at least one circumferential sealing lip which lies onthe cylindrical outer wall region.
 4. The device according to claim 3,wherein the delivery element is guided so as to be locked againstrelative rotation with respect to the housing.
 5. The device accordingto claim 4, which comprises a drive arrangement for the production of arotary movement relative to the housing, wherein the rotary movementbrings about a thrust movement of the delivery element along a thrustaxis.
 6. The device according to claim 5, wherein the delivery elementhas an internal thread, the thread axis of which extends along thethrust axis, and wherein the device comprises a threaded element with anexternal thread in engagement with the internal thread.
 7. The deviceaccording to claim 6, wherein the threaded element is able to be fixedrelative to the housing along the thrust axis and is able to be set intoa rotary movement about the thrust axis by the drive arrangement toadvance the delivery element along the thrust axis.
 8. The deviceaccording to claim 7, wherein the interior of the housing is completelysealed in a fluid-tight manner with respect to the exterior of thehousing.
 9. The device according to claim 1, wherein at least one of thedelivery element and an element cooperating therewith in a sealingmanner comprises a hydrophobic material or is coated hydrophobically.10. The device according to claim 1, wherein at least one of thedelivery element and an element cooperating therewith in a sealingmanner is micro- or nano-structured on a surface to improve the sealingeffect.
 11. The device according to claim 1, wherein at least a firstseal is constructed between the delivery element and a moveable elementmovable relative to the housing, and at least a second seal isconstructed between the movable element and the housing or an elementfixed to the housing.
 12. The device according to claim 11, furthercomprising a changeable reservoir, wherein the movable element is onlymovable on a change of the reservoir and is immovable relative thehousing during the administering.
 13. An injection device comprising ahousing and a delivery element moveable in a liquid-tight manner inrelation to the housing, the delivery element having a cylindrical outerwall region and surrounded by at least one annular sealing element. 14.The device according to claim 13, wherein at least one of the deliveryelement and an element cooperating therewith in a sealing mannercomprises a hydrophobic material or is coated hydrophobically.
 15. Thedevice according to claim 13, wherein at least one of the deliveryelement and an element cooperating therewith in a sealing manner ismicro- or nano-structured on a surface.
 16. The device according toclaim 13, wherein at least a first seal is between the delivery elementand a moveable element movable relative to the housing, and at least asecond seal is between the movable element and one of the housing or anelement fixed to the housing.
 17. The device according to claim 16,further comprising a changeable reservoir, wherein the movable elementis only movable during a change of the reservoir and is immovablerelative the housing during an injection.